Test for glycosides

February 19, 2018
Cardiac Glycosides:

It is a semi quantitative way to learn the current presence of sugars that is polysaccharides. We have to hydrolyze the drug and then chemical examinations are executed. Various examinations tend to be done because of the various chemical entities of this aglycone moiety.

The task the isolation of glycosides in addition varies. The general method is Stass Otto method.
• Powdered medicine is extracted continuously in soxhlet equipment with liquor.
• Extract is treated with lead acetate to precipitate tannins filtered to remove nonglycosidal impurities.
• Excess of lead acetate is precipated as lead sulphide by passing hydrogen sulphide through solution.
• The extract is filtered and concentrated to have crude herb.

They've been classified in accordance with substance nature of aglycone moiety as
1. Anthracene glycosides
2. Cardiac glycosides
3. Saponin glycosides
4. Flavonoidal glycosides
5. Cyanogenetic glycoside
6. Isothiocyanate glycoside
7. Phenol glycoside
8. Alcoholic glycoside
9. Lactone glycoside
10. Bitter glycoside
11. Aldehydic glycoside.

A. Category according to the linkage between aglycone and glycone.
Linkage happens between -OH set of glycone and hydrogen from SH, NH, CH and OH to form:
1. G- glycoside :
Glycone -OH+CH-aglycone'glycone-C-aglycone +water.
e.g. anthracene glycoside-aloe, Flavonoids.
2. O-glycoside: e.g. senna, rhubarb.
3. S-glycoside: Isothiocyanate glycoside this is certainly sinigrin from black colored mustard
4. N- glycoside: they have been within nucleosides in which amino group of base responds
with -OH band of ribose or deoxy ribose to create n-glycoside.

B. They are also categorized based on the form of sugars present:
e.g. Glucoside that have sugar
Rhamnoside that incorporate Rhamnose
Pentoside that have pentose sugars etc.

• they are the glycosides which consists aglycone which is steroidal in nature with α-β unsaturated lactone ring at C-17 position and shows slowing and strengthening impact on a deep failing heart.
• they're present in greater flowers.
• they've been loaded in family apocyanaceae, asclepedaceae, Ranunculaceae, sterculiaceae, leguminosae etc.
• Also, they are present monocots like liliaceae family. E.g. squill.
• also found in frogs.
• those two glycosides are distinguished in line with the presence of 5 or 6 membered lactone ring.
• individuals with five membered lactone ring are cardenolides e.g. digitoxigenin, digoxigenin, gitaloxigenin, gitoxigenin, strophanthidin.
• people that have six membered lactone ring tend to be bufadicaoleates e.g. scillaren A
• optimum flowers includes cardenolides.

• to own activity at C-3 position beta direction is required.
• The ring A, B, C and D must have setup except one element called Uzarin that have trans configuration and sedentary.
• At C-14 OH group present should-be of beta direction, but recently its verified there is no absolute dependence on this to improve the experience.
• At C-17 place unsaturated lactone band is needed but current study demonstrates also open sequence with alpha and beta unsaturation is also enough.
• The sugar moiety affixed at C 3 position of genin consist of 4 sugar products. Including sugar or rhamnose with deoxy sugar like digitoxose.
• Many of them tend to be dissolvable in chloroform and also in alcohols.
• These are typically identified because of the color tests:-

For deoxy sugars, all cardiac glycosides except quobain and squill glycoside that's scillaridin a that do not give e.g. strophanthus and digitalis contains are cardiac glycosides that have deoxy sugars
The sugar is dissolved in acetic acid containing a trace of ferric chloride and transferred to the surface of conc. sulphuric acid. Within junction associated with fluids reddish-brown colour is created which gradually becomes blue.
Baljet tests, Legal examinations, Raymond examinations for the existence of lactone ring.

Substance + sod. Picrate +alkaline 'orange colour.

Substance + sod nitropruside + pyridine+ alkali'red colour.

Substance + dinitro benzene in ethanol +alkali'voilet'blue color.


Source: www.biotecharticles.com
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